The purpose of this study is to investigate the specificity and saturability, hormonal control, chemical nature and distribution of Sertoli cell chromatin acceptor sites (CAS). In an attempt to further define the molecular mechanisms of androgen action on the seminiferous epithelium, the general properties of isolated germ cell chromatin acceptor sites for androgen receptor complexes (ARC) will also be investigated. Nuclei and chromatin will be prepared from cultured Sertoli cells and isolated germ cells. ARC will be partially purified by ammonium sulfate fractionation of cytosols prepared from testes of hypophysectomized rats, prostates and epididymides of castrated rats. The specificity of the binding interaction of testicular CAS with ARC from different sources as well as with other steroid-receptor complexes will be investigated. The saturabilities of CAS of Stertoli cells and fractionated germ cells will be assessed. Furthermore, the effect of androgen on the number of available CAS for ARC and/or the activity of cytosol inhibitory factor(s) in Sertoli cells will be explored. Further efforts will be made to localize Sertoli cell chromatin acceptor sites in chromatin subfractions, i.e., transcriptionally active or inactive, light or heavy, nucleolar or extranucleolar chromatin fractions as well as the nuclear matrix. The fractionation of chromatin subfractions will be achieved by controlled enzymatic digestion or sonication followed by separation based on solubility and sedimentation properties. Systematic partial chromatin deproteinization will be used to localize the Sertoli cell CAS in specific fraction(s) of chromatin components, presumably proteins. An attempt will be made to study the properties, kinetics and nature of the interaction of androgen-receptor complexes with isolated chromatin acceptor fractions covalently bound to agarose, as well as with partially deproteinized and reconstituted Sertoli cell chromatin. The fundamental knowledge gained is crucial to an understanding of the molecular mechanisms by which androgens regulate testicular function.